Sputtered magnetic thin film recording disk

ABSTRACT

The improved sputtered memory disk of the present invention comprises a substrate coated with a nucleating layer, a subsequent magnetic layer, and a protective coating. As a result of texturing in the circumferential direction and epitaxy involving the nucleating layer, an anisotropic orientation of coercivity in the circumferential direction has occurred during the sputtering that provides an improved memory disk having enhanced coercivity, a reduced amplitude modulation, an improved squareness of the hysteresis loop, e.g., lower switching field distribution, and a high production, relatively low cost production system. As a result, a higher recording density due to the higher coercivity and low switching field distribution can be experienced with the magnetic disk of the present invention.

This is a continuation of application Ser. No. 08/250,521, filed on May27, 1994, now abandoned, which is a division of U.S. Ser. No.07/822,589, filed on Jan. 17, 1992, for a MAGNETIC RECORDING DISK ANDSPUTTERING PROCESS AND APPARATUS FOR PRODUCING SAME, (issued as U.S.Pat. No. 5,316,864 on May 31, 1994), which is a division of U.S. Ser.No. 07/464,339, filed on Jan. 12, 1990 (issued as U.S. Pat. No.5,082,747 on Jan. 21, 1992), which is a division of U.S. Ser. No.07/210,119, filed on Jun. 22, 1988 (issued as U.S. Pat. No. 4,894,133 onJan. 16, 1990), which is a division of U.S. Ser. No. 06/926,676, filedon Nov. 3, 1986 (abandoned), which is a division of U.S. Ser. No.06/796,768, filed on Nov. 12, 1985 (issued as U.S. Pat. No. 4,735,840 onApr. 5, 1988).

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an apparatus and a method of depositingmagnetic thin films used for the magnetic recording media in a massproduction, direct current sputtering process and an improved magneticrecording disk product thereby.

2. Description of the Prior Art

The magnetic films that have been used in recording disk and tapesystems have been usually particulate in nature, the magnetic particlesbeing embedded in a binder material and then applied to the substrate.Recently, sputtered and evaporated thin film media have beeninvestigated and utilized for commercial data storage systems. Theadvantages of thinness, low defect level, smoothness and high inductionare particularly adaptable to high recording densities at the desirablelow flying heights of the head pieces. To provide high density recordingit has been recognized that the thin films should exhibit highmagnetization, high coercivity, and a square hysteresis loop. Examplesof thin film material have included cobalt nickel thin films that havebeen deposited upon sublayer films of gold to epitaxially orientate the"C" axis of the cobalt/nickel in the plane of the film.

There have been other suggestions to evaporate cobalt films onto achromium sublayer to increase the coercivity of the cobalt film.Chromium/cobalt deposit film structures have also been suggested usingRF diode sputtering. The chromium layer serves as a nucleating layer toprovide nucleating centers around which a subsequent magnetic film maygrow. Thus, the layer of nucleating material serves to form smallagglomerations that are evenly dispersed over the surface of aninsulating substrate.

Substrates of glass or aluminum alloys have been suggested forsubsequently receiving sputtered deposited layers of chromium cobalt,such as set forth in the article "Sputtered Multi-Layer Films forDigital Magnetic Recording" by Maloney, IEEE Transactions on Magnetics,Volume MAG-15, 3, July 1979. Examples of cobalt nickel magnetic thinfilms are suggested in the article "Effect of Ion Bombardment DuringDeposition on Magnetic Film Properties" by L. F. Herte et al., Journalof the Vacuum Society Technology, Volume 18, No. 2, March 1981.

Finally, the use of a protective layer of carbon in a cobalt chromiumstructure is suggested in "The Optimization of Sputtered Co--Cr LayeredMedium for Maximum Aerial Density" by W. T. Maloney, IEEE TransactionMagnetics Volume Mag-17, No. 6, November 1981. The prior art hasrecognized the importance of reducing the head-gap, the flying heightand the medium thickness but to date has not Suggested a realization ofa low cost commercial process of producing improved magnetic film diskson a production basis to realize the theoretical advantages of certainresearch results. Thus, there is still a need to improve both theapparatus and process of producing and the characteristics of thinmagnetic film disks for commercial utilization.

SUMMARY OF THE INVENTION

The present invention provides a continuous production from a directcurrent planar magnetron sputtering apparatus for the mass production ofmagnetic thin film memory disks, a process for using the same and aresulting improved magnetic thin film memory disk resulting from theprocess.

The apparatus includes a series of pressure reducing entry and exitlocks that are positioned before and respectively after a series of maincoating chambers. The main coating chambers employ planar magnetronsputtering sources located on either side of the travel path of the diskto be coated. A carrier is designed to position a plurality of disksubstrates in a vertical plane for movement through the substratetransport system. Prior to loading on the carrier member, the substratesare pretreated by an abrasion process to provide circumferentialtexturing, e.g. concentric grooves that enhance the magnetic orientationin the plane of the disk. The substrates are mounted on the verticalsubstrate carrier and then subsequently heated, for example, to atemperature of about 100° C. The carrier with the substrates passesthrough an entrance lock slit valve and the initial pressure is reducedfirst by a mechanical pump, then by a cryogenic pump. The carrier thenpasses into a subsequent preliminary coating chamber where a secondpumping system reduces the pressure to enable a sputtering operation.

An inert gas is utilized to provide the plasma gas and can be selectedfrom one of argon and krypton. A relatively high inert gas pressure ispurposely introduced into the main coating chambers to destroy anyanisotropy of coercivity that could occur resulting from the angle ofincidence of the sputtered material as the carrier with the substratedisk approaches and egresses from rectangular planar sputtering sources.The higher gas pressure increases the incidence of collisionalscattering. The substrate carrier enters the first coating chamber andpasses between a pair of elongated direct current planar magnetronsputtering sources positioned on either side of the path of travel ofthe substrate. These sources provide a nucleating layer on both sides ofthe disk substrate and the material can be selected from chromium ortitanium. The nucleating layer favors the epitaxial formation of thesubsequent magnetic thin film layer on top of the nucleating layer. Thesubstrate carrier then passes into a second coating chamber having asecond pair of elongated direct current planar magnetron sputteringsources of a magnetic layer material again on either side of the path oftravel of the substrate carrier. The magnetic layer can be cobalt orpreferably a cobalt alloy, such as cobalt/nickel. The substrate carrierthen passes into the final coating chamber past a third pair ofelongated direct current planar magnetron sources of a protectivecoating material that is positioned on either side of the path of travelof the substrate carrier. The protective coating material is sputteredon top of the thin magnetic film layer to improve both the wearcharacteristics and to protect against corrosion. Various forms ofprotective overcoatings can be utilized, the preferred form beingcarbon. The coated memory disk is then removed from the production linewithout affecting the sputtering operation pressure range through theegressing locks. The disks are then subsequently tested for qualitycontrol and are ready for shipping to a customer.

The improved memory disk of the present invention comprises a substratecoated with chromium with preferably a layer of cobalt/nickel as themagnetic layer sealed with a protective coating of carbon. As a resultof this circumferential texturing, a circular anisotropic crystal growthhas occurred during the sputtering with a circumferential alignment thatprovides an improved memory disk having a reduced amplitude modulation,an improved squareness of the hysteresis loop, e.g. lower switchingfield distribution and a high production relatively low cost productionsystem. As a result, a higher recording linear bit density due to thehigh coercivity and low switching field distribution can be experiencedwith the magnetic disk of the present invention.

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The presentinvention, both as to its organization and manner of operation, togetherwith further objects and advantages thereof, may best be understood byreference of the following description, taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a direct current planar magnetronsputtering process line;

FIG. 2 is a schematic perspective view of the production line;

FIG. 3 is a cross-sectional diagram of a magnetic film recording disk ofthe present invention;

FIG. 4 is a graph of a one revolution read/back voltage envelope showingamplitude modulation characteristics of a recording disk as a result ofsputtering at a low argon pressure;

FIG. 5 is a one revolution read back voltage envelope showing amplitudemodulation characteristics as a result of the sputtering process beingconducted in a high pressure argon gas;

FIG. 6 is a graph of amplitude modulation versus argon sputteringpressure;

FIG. 7 is a graph of switching field distribution versus argonsputtering pressure;

FIG. 8 is a graph of switching field distribution versus radialroughness;

FIG. 9 is a schematic illustration of process for applyingcircumferential texturing to a disk substrate;

FIG. 10 is a graph of coercivity versus thickness of the chromium layer;

FIG. 11 is a perspective view of a cobalt nickel crystal structure;

FIG. 12 is a perspective view of a chromium crystal structure, and

FIGS. 13A and 13B are a combined graph of the hysteresis loop and therelationship of switching field distribution.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description is provided to enable any person skilled inthe thin film deposition art to make and use the invention and setsforth the best modes contemplated by the inventor of carrying out hisinvention. Various modifications, however, will remain readily apparentto those skilled in these arts, since the generic principles of thepresent invention have been defined herein specifically to provide arelatively economical process for manufacturing thin film magnetic disksof an improved structure on a production basis. Referring to FIGS. 1 and2, a direct current planar magnetron sputtering production assembly line2 is shown and comprises from left to right a loading table 4 forreceiving a disk carrier 6, an entrance lock chamber 8 having an outerentrance lock 10 and an inner entrance lock 12.

The main deposition chamber 14 is subdivided into a preliminary chamber16 and sputtering chambers 18, 20 and 22, respectively. An exit chamber24 is the final chamber of the main deposition chamber 14 and ispositioned before the exit lock chamber 26. Finally, an unload table 28is provided along the production line.

As can be seen, the disk carrier 6, which is a flat multi-operationalmetal support plate, is transported through a series of rollers in auni-directional travel from the load table 4 to the unload table 28. Aninner lock valve 30 and an exit lock valve 32 are positioned on eitherside of the exit lock chamber 26. The main deposition chamber 14includes a series of partition walls having central apertures fordividing the respective sputtering chambers. A rotary mechanical pump(not shown) is used to lower the pressure in the entrance lock chamber 8to a pressure of about 0.5×10⁻² torr. Subsequently, a cryogenic pumpcontinues to lower the pressure to 2×10⁻⁵ torr, prior to the entrancelock chamber 8 being back-filled with relatively pure argon (99.99%) ata pressure of 2×10⁻² torr. The entrance lock chamber pump 34 iscomplemented with a pair of main deposition chamber pumps 36 and 38.Finally, an exit lock chamber pump 40 is provided to evacuate the exitlock chamber 26.

The disk carrier 6 is particularly designed to be maintained in avertical plane as it passes through the main desposition chamber 14. Thefirst sputtering chamber 18 is provided with four direct current planarmagnetron sputtering sources 42 for providing a nucleating layer. Thesources 42 are approximately five inches wide by fifteen inches inlength and are approximately 3/8 of an inch thick with direct watercooling. The main deposition chamber 14 is also filled with argon at apressure of 2×10⁻² torr. This pressure range is relatively high for a DCplanar magnetron sputtering system since it is usually preferably tooperate at a much lower pressure to maximize the deposition rate of thetarget material. The use of the relatively high pressure of argon gasfor a DC planar magnetron sputtering procedure is specifically toprevent direct collision of the ions with the substrate disk at lowangles of incidence as the disk carrier 6 progressively moves throughthe assembly line 2. Usually the speed of the substrate transport systemfor the disk carrier 6 is a velocity within a range of 1 to 10 mm/sec,with a typical average speed of 3 mm/sec.

The next sputtering chamber 20 provides the magnetic layer and includestwo magnetron sputtering sources 44 positioned on either side of theline of travel of the disk carrier 6. The target dimensions areapproximately the same as the nucleating targets 42 and can, forexample, be cobalt/nickel alloy source 44. Finally, sputtering chamber22 includes a protective coating source 46, such as carbon, that againcomprises a pair of sources one on each side of the line of travel ofthe disk carrier 6. Each of the sources are essentially line sourceswith cosine distribution of their emission profile. The target spacingfor an opposing pair is 5 1/2 inches with a target to substrate spacingof approximately 2 1/4 inches preferred. The target source to substratedistance is preferably maintained within a range of 2 to 4 inches.

The direct current planar magnetron sources 42, 44 and 46 can use bothpermanent magnets or electro magnets for plasma confinement. Each sourceis independently powered by constant current 10 kw direct power supply.

Referring to FIG. 3, a substrate 50 can be selected from glass, anelectroless plated nickel over aluminum alloy where the aluminum alloyis 5086, pure aluminum or a polycarbonate or a polyetheramide plastic.The substrate dimensions can be in the range of 95 mm to 230 mm in outerdiameter with a thickness of 0.035 to 0.080 inches. The arithmeticaverage of the substrate smoothness should be about 75 to 100 angstroms.The nucleating layer 52 can be selected from chromium and titanium.Preferably, chromium is selected in the preferred embodiment.

As shown in FIG. 12, the chromium underlayer 52 provides a BCC (bodycentered cubic) structure with a (110) orientation of itscrystalographic plane parallel to the plane of the substrate disk 50.This (110) orientation provides the appropriate lattice parameter toinitiate the epitaxial growth in the magnetic thin film layer of a HCP(hexagonal close packed) phase with a (1010) orientation that is the "C"axis is parallel to the substrate 50. Reference can be had to FIG. 11 toshow such an orientation of a cobalt/nickel alloy. As can be appreciatedby these skilled in this field, it is highly desirable to have thehexagonal close pack phase (HCP) of the magnetic thin film layerorientated parallel to the plane of the disk for longitudinal recording.Generally, the depositing of the magnetic film material, such as thecobalt/nickel film, directly on a glass or aluminum substrate willobtain a FCC (Face Center Cubic) structure. However, the use of anucleating layer will provide the preferred orientation.

The thickness of the nucleating layer of chromium is within a range of1000 to 5000 angstroms. A preferred thickness for the nucleating layercan be approximately 3000 angstroms of chromium. The magnetic layer 54can be selected from one of cobalt, a cobalt/nickel alloy, acobalt/chromium alloy and a cobalt/vanadium alloy. In the cobalt/nickeland 65% to 100% cobalt alloys a range of 0 to 35% nickel and 65% to 100%cobalt could be utilized while in the cobalt/chromium alloys a range of5 to 25% chromium could be utilized, and in the cobalt/vanadium alloys a5 to 25% range of vanadium could be utilized. The thickness of themagnetic layer is approximately 200 to 1200 angstroms and is preferablyin the range of approximate 750 angstroms.

Finally, a protective overcoat 56 is provided for wear resistance andcorrosion resistance. It is believed that titanium carbide, Boroncarbide and tungsten carbide could be utilized. The preferred protectiveovercoating is carbon having a layer thickness in the range of 200 to800 angstroms with 300 angstroms being an approximate preferred coatingthickness.

To achieve a high volume production with a continuous on-line sputteringprocess, disk carriers 6 are progressively moved through apertures ineach of the sputtering chambers 18, 20 and 22. The purpose of providinga nucleating layer 52 is to permit a "C" axis texture to be formed inthe subsequent magnetic layer 54 in a random manner. A problem hasoccurred, however, in that an anisotropic "C" axis texture is promotedby an early arrival of chromium atoms as the substrate enters throughthe aperture of the chamber 18 and the very large angle of incidenceresulting from the movement of the substrates during the constantsputtering process. This anisotropy of the "C" axis causes an anisotropyof coercivity which will produce a severe once around amplitudemodulation in an output signal recorded on the magnetic layer 52. Thisis a particularly objectionable property for a high density longitudinalrecording. This problem is graphically disclosed in FIG. 4 wherein aplus or minus 25% amplitude modulation has been experienced.

The present invention by providing a relatively high argon pressurerelative to a direct current planar magnetron sputtering process,removes this problem of anisotropic orientation by providing a randomdistribution of the sputtered atoms (presumably resulting from acollisional phenomena with the argon atoms at the relatively highpressure). Referring specifically to FIG. 6, the relationship betweenthe amplitude modulation of the read/back voltage and the argonsputtering pressure is graphically disclosed. As can be seen from thisgraph, higher pressure reduced the modulation while lower pressureswould increase the modulation.

Referring to FIG. 7, the relationship to switching field distribution(SFD) is disclosed for the magnetic layer as it varies with the argonsputtering pressures. The SFD at lower pressures is correspondingly low,and at the higher pressures the SFD value is high. It is believed thatthis occurs because the larger and more uniform grain size is promotedat lower pressures and more variant grain sizes are promoted at higherpressures.

A lower SFD value, typically below 0.20 is particularly advantageous forhigh density magnetic recording since such values allow a highresolution of the recording bit transitions. By comparing FIGS. 6 and 7,it can be seen that the low argon pressures have an advantage withregard to the SFD value but provide a disadvantage with regard toamplitude modulation. Thus, a design factor in the present invention isa compromise in providing an argon pressure such as a range of 2.0 to4.0×10⁻² torr. In operation, the present invention could utilize aplasma gas pressure range from 1×10⁻² torr. Operation below 1×10⁻² torrcan increase the amplitude modulation by a ±15% operation above 7.5×10⁻²torr permits the columnar structure of the thin film to become tooporous and rough for permitting the recording head to fly close to thedisk surface. As those skilled in the art know, the closer the recordinghead can fly to the recording disk, the more efficient will be the readand write recording. Recording heads typically fly above the surface ofthe disk, supported by an air cushion at a distance of 6 to 12 microinches. Irregularities on the surface of the recording disk that couldinterfere or contact the recording head must be avoided.

FIG. 4 and FIG. 5 are representations of oscilloscope voltage traces forone revolution of travel around a disk circumference while sending theread/back signal from a high frequency 2 F MFM written pattern. FIG. 4shows the read/back voltage modulated by ±25% which is an unacceptablevalue for present day magnetic recording read/write channels.

FIG. 5 shows the read/back voltage modulated by ±5% which is a valuenecessary for the highest performance from a magnetic recording diskdevice.

The read/back signal amplitude modulation shown in FIG. 4 is caused byanisotropic orientation of the HCP "C" axis of the cobalt/nickel layershown in FIG. 11. This anisotropic orientation is in the plane of thedisk parallel to the direction of traverse passing the sputteringsources due to the sputtering of all layers at lower pressures(typically below 2.0×10⁻² torr) and consequently inducing a low angle ofincidence columnar film growth in preference to the direction of thesubstrate as it passes the sources.

This HCP "C" axis anisotropy causes the resulting film coercivity tohave a similar directional anisotropy and consequently causes variationsin the read/back signal voltage at varying circumferential positions asthe head travels around the disk in one revolution.

FIG. 5 shows a reduced modulation amplitude of the read/back voltagesignal due to a sputtering operation at higher pressures (typically2.0×10⁻² to 4.0×10⁻² torr).

Sputtering at these higher pressures causes collisional scattering ofsputtered atoms before they reach the substrate and hence a more randomfilm structure, which includes the random orientation of the HCP "C"axis of the cobalt/nickel layer in the plane of the disk, therebyeliminating any low angle of incident effects.

To improve the magnetic recording density, it is important to provide arelatively high squareness to the hysteresis loop as disclosed in FIG.13. The randomizing of the "C" axis by the increased gas pressure of thepresent invention lowers the amplitude modulation but only provides amodest squareness to the hysteresis loop.

The present invention has discovered that circumferential texturing orabrading of the disk surface can cause the "C" axis to orientate in acircumferential direction and thereby supply a more intense uniformcontinuous read/back signal to the flying head with a resulting verysquare hysteresis loop. Thus, a preliminary abrading of the substrate asshown in FIG. 9 is an advantage of the present invention. As mentionedearlier, one of the design goals in this art is to permit the recordinghead to fly as close as possible to the surface of the recording disk.The abrading step on the substrate would appear to be contrary to thisteaching. In fact, excessive roughness to the substrate will provide alimitation to the closeness by which the head can fly to the finishedrecording disk.

In FIG. 9, a substrate 58, such as a nickel plated aluminum member ispositioned on a rotating shaft 60 and rotated at a speed less than 200rpm. A diamond impregnated polyester tape 62 is applied to both sides ofthe disk substrate 58 to abrasively remove the nickel plating from thesubstrate in the shape of concentric grooves 66 roughly proportional tothe size of the diamond abrasive in the tape. Generally, the particlesize of the abrasive is typically in the range of 0.1 to 1.0 microns.This circumferential texturing can be accomplished by rotating thesubstrate 58 while pressing the diamond impregnated polyester tape 62against both sides of the disk in the presence of a fluid coolant, likekerosene, supplied through a nozzle 64. The coolant not only controlsthe temperature of the abrading process but also acts to remove anymicroscopic abraded debris.

Referring to FIG. 8, the relationship between the switching fielddistribution (SFD) and the radial roughness of the finished disk due tocircumferential texturing is disclosed. As the disk surface radialroughness increases due to a deliberate circumferential grooving the SFDdecreases. A low SFD is a desirable parameter for high densityrecording. It is believed that the physical cause of this effect is thepreferential orientation of the "C"-axis of the HCP phase of, forexample, a cobalt/nickel magnetic layer along a circumferential texturalline. It is also believed that this occurs primarily due to anyshadowing effects of the hills and valleys of the texturing. Theroughness factor should be in the range of 50 to 500 angstroms. Aroughness factor below 50 angstroms promotes higher switching fielddistribution and permits a more random "C" axis orientation. A roughnessor hill to valley distance above 500 angstroms can interfere with thefly chracteristics of the recording head.

Referring again to FIGS. 1 and 2, a substrate disk, such as anelectroless plated nickel over aluminum alloy, with the aluminum alloybeing 5086 can be circumferentially textured as shown in FIG. 9 to aradial roughness factor of 200 angstroms prior to being loaded on to thedisk carrier 6. Usually, the substrates are preparatorily cleaned withdeionized water, a detergent of a non-ionic surfactant and ultrasonics(10 to 60 kilohertz). The substrates can also be inserted into a vaporphase of a trichlorotrifluoroethane vapor dryer. The substrate can alsobe preliminarily heated to 100 degrees Centrigrade as an additionalpreparatory step.

The cleaned and heated substrate can then be loaded onto disk carrier 6which then subsequently enters the entrance lock chamber 8, and when theouter door is closed the entrance lock chamber can be evacuated by arotary mechanical pump and then subsequently by a cryogenic pump 34. Thelock chamber 8 is filled with argon gas at a pressure of 2×10⁻² torr.The main deposition chamber 14 has been previously evacuated and pumpedto a base pressure of 2×10⁻⁷ torr as a result of the two cryogenic pumps36 and 38. This chamber is also filled with argon gas at a pressure of2×10⁻² torr. The disk carrier 6 then moves at a constant velocitythrough the respective sputtering chambers 18 through 22. Power issupplied to all of the sputtering sources, as more particularly seen inFIG. 2 and a plasma is initiated over each source to commence thesputtering. The entrance lock inner door or valve 12 opens and thevertically orientated disk carrier 6 moves forward at a speed ofapproximately 3 mm/sec. 3 kw of power are supplied to each of the fourchromium sources 42 which are utilized for the nucleating layer 52 asshown in FIG. 3. 2.5 kw of power is supplied to each of the twocobalt/nickel layer sources and 2.5 kw is supplied to each of the twocarbon protective layer sources. As the disk carrier 6 traverses pasteach of the deposition sources, they are uniformly coated, first with anucleating layer 52, then the magnetic layer 54 and finally theprotective layer 56. The actual substrate temperature willadvantageously be maintained by a heater 15 in a temperature range of 75degress Centigrade to 250 degrees Centigrade. A temperature below 75degrees Centigrade will not permit a reliable adhesion of the thin filmlayers while a temperature above 250 degrees Centigrade can create awarp in the substrate disk and can cause the nickel phosphorous layer tobecome magnetic. It is believed that this may be caused by the migrationof the phosphorous to the grain boundaries at the higher temperature.

The actual thickness layer of the nucleating layer of chromium is withinthe range of 1000 to 5000 angstroms, and FIG. 10 discloses a graph ofcoercivity versus the chromium layer thickness. This graph was derivedfor a cobalt/nickel 80:20 alloy thickness with an argon pressure of2×10⁻² torr and a substrate temperature of 200 degrees Centigrade. Ascan be seen, for a given cobalt/nickel layer thickness coercivityincreases with increasing chromium thickness and for a given chromiumthickness coercivity decreases with an increasing cobalt/nickelthickness.

A magnetic layer, such as a cobalt/nickel alloy is deposited within therange of 200 to 1500 angstroms, and finally a protective coating, suchas carbon, is deposited within the range of 200 to 800 angstroms. Thedisk carrier then transports the finished coated magnetic recording diskto the exit lock chamber 26 which has been previously evacuated andpumped to 2×10⁻⁵ torr and then back filled with argon to 2×10⁻² torr.The interlock valve 30 is closed and the exit lock 32 is vented toatmospheric pressure with argon in less than 20 seconds. The diskcarrier 6 exits the exit lock 32 and the finished recording disks areunloaded for quality control testing. The empty disk carriers 6 arereturned for reloading for a subsequent production cycle.

Referring to FIGS. 13A and 13B, the switching field distribution (SFD)defines a measure of the change in the drive field requirements toswitch the magnetic domains of the magnetic layer. Graphically, thisparameter is defined by means of an unintegrated or differential curve.By constructing a horizontal line at a vertical coordinate of one halfthe peak value, two points of the intersection result are defined as thehorizontal distance between these points. Delta H is defined as thehorizontal distance between these points. SFD is defined as divided bythe coercivity Hc. Hc is shown at the width of the hysteresis loop shownat the bottom of the graph in FIG. 13B.

While the above features of the present invention teach apparatus,process and an improved magnetic recording disk, it can be readilyappreciated that it would be possible to deviate from the aboveembodiments of the present invention and, as will be readily understoodby those skilled in the art, the invention is capable of manymodifications and improvements within the scope and spirit thereof.Accordingly, it will be understood that the invention is not to belimited by the specific embodiments but only by the spirit and scope ofthe appended claims.

I claim:
 1. A magnetic thin film recording disk formed by a series ofsequential sputtering processes within an environment of a low pressureinert gas, comprising:a substrate having a nickel phosphorous surfacelayer, the substrate including aluminum, the substrate characterized bya surface having texturing in a circumferential direction prior to anysputtering operation contributing to an anisotropic orientation ofcoercivity in the circumferential direction while not interfering withfly characteristics of a recording head across the recording disk, anRa, arithmetic average radial roughness of the texturing contributing toa magnetic switching field distribution of less than 0.20; a thin filmnucleating layer containing chromium, and substantially free ofoxidation, deposited above the textured nickel phosphorous surface by afirst sputtering process; a thin film magnetic layer containing a cobaltalloy deposited above the nucleating layer by a second sputteringprocess and having an anisotropic orientation of coercivity in thecircumferential direction; and a thin film protective layer containingcarbon deposited above the magnetic layer by a third sputtering process.2. The magnetic thin film recording disk of claim 1, wherein the Ra,arithmetic average radial roughness of circumferential texturing of thefinished recording disk is in a range of 0.18 microinches to 0.6microinches.
 3. The magnetic thin film recording disk of claim 1,wherein the substrate is in a range of approximately 95 mm to 230 mm inouter diameter.
 4. The magnetic thin film recording disk of claim 1,wherein the cobalt alloy has a hexagonal close-packed phase with itsC-axis oriented substantially parallel to the surface of the disk. 5.The magnetic thin film recording disk of claim 1, wherein the cobaltalloy has a hexagonal close-packed phase with its C-axis orientedsubstantially in the circumferential direction.
 6. The magnetic thinfilm recording disk of claim 1, wherein the substrate is heated to atemperature within a range of 200° C. to 250° C. during the sputteringprocess.
 7. The magnetic thin film recording disk of claim 1 wherein thesubstrate is heated to a temperature within a range of 75° C. to 250° C.during the sputtering process.
 8. The magnetic thin film recording diskof claim 1 wherein the texturing, prior to any sputtering operation,encourages a circular anisotropic orientation of crystal growth duringsputtering.
 9. A magnetic thin film recording disk formed by a series ofsequential sputtering processes within an environment of a low pressureinert gas, comprising:a substrate having a nickel phosphorous surfacelayer, the substrate including aluminum, the substrate characterized bya surface having texturing in a circumferential direction prior to anysputtering operation contributing to an anisotropic orientation ofcoercivity in the circumferential direction, while not interfering withfly characteristics of a recording head across the recording disk, anRa, arithmetic average radial roughness of the texturing contributing toreduced amplitude modulation, any output of a signal recorded on themagnetic thin film recording disk will have an amplitude modulation, andthe amplitude modulation will be less than 25 percent; a thin filmnucleating layer containing chromium and substantially free ofoxidation, deposited above the textured nickel phosphorous surface by afirst sputtering process; a thin film magnetic layer containing a cobaltalloy deposited above the nucleating layer by a second sputteringprocess and having an anisotropic orientation of coercivity in thecircumferential direction; and a thin film protective layer containingcarbon deposited above the magnetic layer by a third sputtering process.10. The magnetic thin film recording disk of claim 9, wherein the Ra,arithmetic average radial roughness of circumferential texturing of thefinished recording disk is in a range of 0.18 microinches to 0.6microinches.
 11. The magnetic thin film recording disk of claim 9,wherein the substrate is heated to a temperature within a range of 200°C. to 250° C. during the sputtering process.
 12. The magnetic thin filmrecording disk of claim 9 wherein the substrate is heated to atemperature within a range of 75° C. to 250° C. during the sputteringprocess.
 13. A magnetic thin film recording disk formed by a series ofsequential sputtering processes within an environment of a low pressureinert gas, comprising:a substrate characterized by a surface havingtexturing in a circumferential direction prior to any sputteringoperation contributing to an anisotropic orientation of coercivity inthe circumferential direction, while not interfering with flycharacteristics of a recording head across the recording disk, an Ra,arithmetic average radial roughness of the texturing contributing to amagnetic switching field distribution of less than 0.20, any output of asignal recorded on the magnetic thin film recording disk having anamplitude modulation, the amplitude modulation being less than 25percent; a thin film nucleating layer, substantially free of oxidation,deposited above the textured substrate surface by a first sputteringprocess; a thin film magnetic layer containing a cobalt alloy depositedabove the nucleating layer by a second sputtering process and having ananisotropic orientation of coercivity in the circumferential direction;and a thin film protective layer containing carbon deposited above themagnetic layer by a third sputtering process.
 14. The magnetic thin filmrecording disk of claim 13, wherein the Ra, arithmetic average radialroughness of circumferential texturing of the finished recording disk isin a range of 0.18 microinches to 0.6 microinches.
 15. The magnetic thinfilm recording disk of claim 13, wherein the substrate is about 95 mm to230 mm in outer diameter.
 16. The magnetic thin film recording disk ofclaim 13, wherein the substrate is nickel phosphorus plated aluminumwhich was heated to a temperature within a range of 200° C. to 250° C.during the sputtering process.
 17. The magnetic thin film recording diskof claim 13, wherein the cobalt alloy has a thickness between 200angstroms to 1500 angstroms.
 18. The magnetic thin film recording diskof claim 13, wherein the nucleating layer and the magnetic layer have anorientation of crystal growth characteristic of linearly moving thesubstrate during a D.C. planar magnetron sputtering deposition of eachlayer.
 19. The magnetic thin film recording disk of claim 13, whereinthe substrate is selected from one of glass, plastic, and aluminum. 20.The magnetic thin film recording disk of claim 13, wherein thenucleating layer contains chromium.
 21. The magnetic thin film recordingdisk of claim 20, wherein the carbon containing protective film isbetween approximately 200 angstroms and 800 angstroms.
 22. The magneticthin film recording disk of claim 20, wherein the cobalt alloy isselected from one of a cobalt/nickel alloy, a cobalt/chromium alloy, anda cobalt/vanadium alloy having a thickness within a range of 200 to 1500angstroms.
 23. The magnetic thin film recording disk of claim 22,wherein the protective layer has a thickness within a range ofapproximately 200 to 800 angstroms.
 24. The magnetic thin film recordingdisk of claim 13 wherein the substrate is heated to a temperature withina range of 75° C. to 250° C. during the sputtering process.
 25. Amagnetic thin film recording disk formed by a series of sequentialsputtering processes within an environment of a low pressure inert gas,comprising:a substrate characterized by a surface having texturing in acircumferential direction prior to any sputtering operation to encouragea circular anisotropic orientation of crystal growth during sputtering,while not interfering with fly characteristics of a recording headacross the recording disk, an Ra, arithmetic average radial roughness ofcircumferential texturing contributing to a magnetic switching fielddistribution of less than 0.20; a thin film nucleating layer depositedabove the textured surface by a first sputtering process; a thin filmmagnetic layer deposited above the nucleating layer by a secondsputtering process and having an anisotropic orientation of coercivityin the circumferential direction; and a thin film protective layerdeposited above the magnetic layer by a third sputtering process. 26.The magnetic thin film recording disk of claim 25 wherein thetemperature of the substrate is heated to a temperature within a rangeof 200° C. to 250° C.
 27. The magnetic thin film recording disk of claim25 wherein the substrate is heated to a temperature within a range of75° C. to 250° C. during the sputtering process.
 28. A magnetic thinfilm recording disk formed by a series of sequential sputteringprocesses within an environment of a low pressure inert gas,comprising:a substrate characterized by a surface having texturing in acircumferential direction prior to any sputtering operation to encouragea circular anisotropic orientation of crystal growth during sputtering,while not interfering with fly characteristics of a recording headacross the recording disk, an Ra, arithmetic average radial roughness ofcircumferential texturing contributing to reduced amplitude modulationsuch that any output of a signal recorded on the magnetic thin filmrecording disk will have an amplitude modulation, and the amplitudemodulation will be less than 25 percent; a thin film nucleating layerdeposited above the textured surface by a first sputtering process; athin film magnetic layer deposited above the nucleating layer by asecond sputtering process and having an anisotropic orientation ofcoercivity in the circumferential direction; and a thin film protectivelayer deposited above the magnetic layer by a third sputtering process.29. The magnetic thin film recording disk of claim 28 having a magneticswitching field distribution of less than 0.20.
 30. The magnetic thinfilm recording disk of claim 29, wherein the substrate has a nickelphosphorus plated surface layer.
 31. The magnetic thin film recordingdisk of claim 29, wherein the Ra, arithmetic average radial roughness ofthe finished recording disk is in a range of 0.18 microinches to 0.6microinches.
 32. The magnetic thin film recording disk of claim 31,wherein the substrate includes aluminum.
 33. The magnetic thin filmrecording disk of claim 32, wherein the aluminum substrate is coatedwith nickel phosphorus.
 34. The magnetic thin film recording disk ofclaim 33, wherein the orientation of crystal growth for the nucleatinglayer and magnetic layer are characteristic of linearly moving thesubstrate during a D.C. planar magnetron sputtering deposition of eachlayer.
 35. The magnetic thin film recording disk of claim 33, whereinthe temperature of the substrate is within a range of 200° C. to 250° C.during the sputtering process.
 36. The magnetic thin film recording diskof claim 28 wherein the temperature of the substrate is heated to atemperature within a range of 200° C. to 250° C.
 37. The magnetic thinfilm recording disk of claim 28 wherein the substrate is heated to atemperature within a range of 75° C. to 250° C. during the sputteringprocess.
 38. A magnetic thin film recording disk formed by a series ofsequential sputtering processes within an environment of a low pressureinert gas, comprising:a substrate characterized by a surface having atexturing in a circumferential direction prior to any sputteringoperation to encourage a circular anisotropic orientation of crystalgrowth during sputtering, while not interfering with fly characteristicsof a recording head across the recording disk, an Ra, arithmetic averageradial roughness of the texturing contributing to a magnetic switchingfield distribution of less than 0.20, any output of a signal recorded onthe magnetic thin film recording disk having an amplitude modulation,the amplitude modulation being less than 25 percent; a thin filmnucleating layer deposited above the textured substrate surface by afirst sputtering process; a thin film magnetic layer containing a cobaltalloy deposited above the nucleating layer by a second sputteringprocess and having an anisotropic orientation of coercivity in thecircumferential direction; and a thin film protective layer depositedabove the magnetic layer by a third sputtering process.
 39. The magneticthin film recording disk of claim 38 wherein the temperature of thesubstrate is heated to a temperature within a range of 200° C. to 250°C.
 40. The magnetic thin film recording disk of claim 38 wherein thesubstrate is heated to a temperature within a range of 75° C. to 250° C.during the sputtering process.
 41. A magnetic thin film recording diskformed by a series of sequential sputtering processes within anenvironment of a low pressure inert gas, comprising:a substrate having anickel phosphorous layer, the substrate characterized by a surfacehaving texturing in a circumferential direction prior to any sputteringoperation to encourage a circular anisotropic orientation of crystalgrowth during sputtering, while not interfering with fly characteristicsof a recording head across the recording disk, an Ra, arithmetic averageradial roughness of a circumferential texturing of the finished diskbeing in a range of 0.18 microinches to 0.6 microinches for contributingto a magnetic switching field distribution of less than 0.20; a thinfilm nucleating layer containing chromium deposited above the texturednickel phosphorous surface by a first sputtering process; a thin filmmagnetic layer containing a cobalt alloy deposited above the nucleatinglayer by a second sputtering process and having an anisotropicorientation of coercivity in the circumferential direction; and a thinfilm protective layer containing carbon deposited above the magneticlayer by a third sputtering process.
 42. The magnetic thin filmrecording disk of claim 41 wherein the temperature of the substrate isheated to a temperature within a range of 200° C. to 250° C.
 43. Themagnetic thin film recording disk of claim 41 wherein the substrate isheated to a temperature within a range of 75° C. to 250° C. during thesputtering process.
 44. A magnetic thin film recording disk formed by aseries of sequential sputtering processes within an environment of a lowpressure inert gas, comprising:a glass substrate being characterized bya surface having texturing in a circumferential direction prior to anysputtering operation to encourage a circular anisotropic orientation ofcrystal growth during sputtering, while not interfering with flycharacteristics of a recording head across the recording disk, an Ra,arithmetic average radial roughness of the circumferential texturing ofthe finished disk contributing to a magnetic switching fielddistribution of less than 0.20; a nucleating layer deposited above thetextured glass surface by a first sputtering process; a magnetic layercontaining a cobalt alloy deposited above the nucleating layer by asecond sputtering process and having an anisotropic orientation ofcoercivity in the circumferential direction; and a protective layercontaining carbon deposited above the magnetic layer by a thirdsputtering process.
 45. The magnetic thin film recording disk of claim45 wherein the temperature of the substrate is heated to a temperaturewithin a range of 200° C. to 250° C.
 46. The magnetic thin filmrecording disk of claim 41 wherein the substrate is heated to atemperature within a range of 75° C. to 250° C. during the sputteringprocess.
 47. A magnetic thin film recording disk formed by a series ofsequential sputtering processes within an environment of a low pressureinert gas, comprising:a glass substrate being characterized by a surfacehaving texturing in a circumferential direction prior to any sputteringoperation contributing to an anisotropic orientation of coercivity inthe circumferential direction during sputtering, while not interferingwith fly characteristics of a recording head across the recording disk,an Ra, arithmetic average radial roughness of the circumferentialtexturing of the finished disk contributing to a magnetic switchingfield distribution of less than 0.20; a nucleating layer, substantiallyfree of oxidation, deposited above the textured glass surface by a firstsputtering process; a magnetic layer containing a cobalt alloy depositedabove the nucleating layer by a second sputtering process and having ananisotropic orientation of coercivity in the circumferential direction;and a protective layer containing carbon deposited above the magneticlayer by a third sputtering process.
 48. The magnetic thin filmrecording disk of claim 47, wherein the thin film magnetic layercontains a hexagonal close-packed cobalt alloy.
 49. The magnetic thinfilm recording disk of claim 47 wherein the temperature of the substrateis heated to a temperature within a range of 200° C. to 250° C.
 50. Themagnetic thin film recording disk of claim 47 wherein the substrate isheated to a temperature within a range of 75° C. to 250° C. during thesputtering process.
 51. A magnetic thin film recording disk formed by aseries of sequential sputtering processes within a continuous productionenvironment of a low pressure inert gas, comprising:a substratecharacterized by a surface having texturing in a circumferentialdirection prior to any sputtering operation contributing to ananisotropic orientation of coercivity in the circumferential directionwhile not interfering with fly characteristics of a recording headacross the recording disk; a thin film nucleating layer deposited abovethe substrate by a first sputtering process; a thin film magnetic layercontaining a hexagonal close-packed cobalt alloy deposited over thenucleating layer by a second sputtering process and having ananisotropic orientation of coercivity in the circumferential direction;and a thin film protective layer containing carbon deposited above themagnetic layer by a third sputtering process.
 52. The magnetic thin filmrecording disk of claim 51, wherein the thin film magnetic layer has acharacteristic that any output of a signal recorded on the magnetic thinfilm recording disk will have an amplitude modulation, and the inert gaspressure during sputtering being set at a sputtering pressure level sothat the amplitude modulation will be less than 25 percent, wherein thesubstrate surface is textured prior to any sputtering operation tocontribute to a magnetic switching field distribution of less than 0.20.53. The magnetic thin film recording disk of claim 51, wherein thesubstrate surface is textured prior to any sputtering operation tocontribute to a magnetic switching field distribution of less than 0.20.54. The magnetic thin film recording disk of claim 51, wherein the thinfilm magnetic layer has a characteristic that any output of a signalrecorded on the magnetic thin film recording disk will have an amplitudemodulation, and the inert gas pressure during sputtering being set at asputtering pressure level so that the amplitude modulation will be lessthan 25 percent.
 55. The magnetic thin film recording disk of claim 51,wherein the thin film protective layer has a thickness within a range ofabout 200 to 800 angstroms.
 56. The magnetic thin film recording disk ofclaim 51, wherein the magnetic layer has an orientation of a C-axis ofthe cobalt alloy substantially parallel to the surface of the substrate.57. The magnetic thin film recording disk of claim 56, wherein the thinfilm nucleating layer contains chromium.
 58. The magnetic thin filmrecording disk of claim 57, wherein the thin film magnetic layer isselected from one of a cobalt/nickel alloy, a cobalt/chromium alloy, anda cobalt/vanadium alloy.
 59. The magnetic thin film recording disk ofclaim 57, wherein the thin film magnetic layer has a thickness within arange of about 200 to 1500 angstroms.
 60. The magnetic thin filmrecording disk of claim 51, wherein the magnetic layer has anorientation of a C-axis of the cobalt alloy substantially in thecircumferential direction.
 61. The magnetic thin film recording disk ofclaim 51 wherein the temperature of the substrate is heated to atemperature within a range of 200° C. to 250° C.
 62. The magnetic thinfilm recording disk of claim 51 wherein the substrate is heated to atemperature within a range of 75° C. to 250° C. during the sputteringprocess.
 63. A magnetic thin film recording disk formed by a series ofsequential sputtering processes within an environment of a low pressureinert gas, comprising:a substrate having a nonmagnetic surface layer,the substrate including aluminum, the substrate characterized by asurface having texturing in a circumferential direction prior to anysputtering operation contributing to an anisotropic orientation ofcoercivity in the circumferential direction while not interfering withfly characteristics of a recording head across the recording disk, athin film nucleating layer deposited above the textured surface by afirst sputtering process; a thin film magnetic layer containing ahexagonal closed packed cobalt alloy deposited above the nucleatinglayer by a second sputtering process and having an anisotropicorientation of coercivity in the circumferential direction; and a thinfilm protective layer containing carbon deposited above the magneticlayer by a third sputtering process.
 64. The magnetic thin filmrecording disk of claim 63, wherein the nucleating layer containschromium.
 65. The magnetic thin film recording disk of claim 63, whereina C-axis of the magnetic layer is orientated substantially parallel tothe surface of the substrate.
 66. The magnetic thin film recording diskof claim 63, wherein a C-axis of the magnetic layer is orientatedsubstantially in the circumferential direction.
 67. The magnetic thinfilm recording disk of claim 63, wherein the substrate is heated to atemperature within a range of 200° C. to 250° C. during the sputteringprocess.
 68. The magnetic thin film recording disk of claim 63 whereinthe substrate is heated to a temperature within a range of 75° C. to250° C. during the sputtering process.
 69. The magnetic thin filmrecording disk of claim 63 wherein the texturing, prior to anysputtering operation, encourages a circular anisotropic orientation ofcrystal growth during sputtering.
 70. A magnetic thin film recordingdisk formed by a series of sequential sputtering processes within anenvironment of a low pressure inert gas, comprising:a substratecharacterized by a surface having texturing in a circumferentialdirection prior to any sputtering operation contributing to ananisotropic orientation of coercivity in the circumferential directionwhile not interfering with fly characteristics of a recording headacross the recording disk, a thin film nucleating layer, substantiallyfree of oxidation, deposited above the textured surface by a firstsputtering process; a thin film magnetic layer, substantially free ofoxidation, deposited above the nucleating layer by a second sputteringprocess and having an anisotropic orientation of coercivity in thecircumferential direction; and a thin film protective layer depositedabove the magnetic layer by a third sputtering process.
 71. The magneticthin film recording disk of claim 70, wherein the temperature of thesubstrate is within a range of 200° C. to 250° C. during the sputteringprocess.
 72. The magnetic thin film recording disk of claim 70, whereinthe nucleating layer contains chromium.
 73. The magnetic thin filmrecording disk of claim 70, wherein the magnetic layer contains ahexagonal closed packed cobalt alloy which has a C-axis orientationsubstantially parallel to the surface of the substrate.
 74. The magneticthin film recording disk of claim 70, wherein the magnetic layercontains a hexagonal closed packed cobalt alloy which has a C-axisorientation substantially in the circumferential direction.
 75. Themagnetic thin film recording disk of claim 70 wherein the substrate isheated to a temperature within a range of 75° C. to 250° C. during thesputtering process.
 76. The magnetic thin film recording disk of claim70 wherein the texturing, prior to any sputtering operation, encouragesa circular anisotropic orientation of crystal growth during sputtering.77. A magnetic thin film recording disk formed by a series of sequentialsputtering processes within an environment of a low pressure inert gas,comprising:a substrate having a nickel phosphorous surface layer, thesubstrate including aluminum, the substrate characterized by a surfacehaving texturing in a circumferential direction prior to any sputteringoperation contributing to an anisotropic orientation of coercivity inthe circumferential direction while not interfering with flycharacteristics of a recording head across the recording disk; a thinfilm nucleating layer containing chromium, substantially free ofoxidation, deposited over the textured nickel phosphorous surface by afirst sputtering process; a thin film magnetic layer containing ahexagonal close-packed cobalt alloy deposited over the nucleating layerby a second sputtering process and having an anisotropic orientation ofcoercivity in the circumferential direction; and a thin film protectivelayer containing carbon deposited over the magnetic layer by a thirdsputtering process.
 78. The magnetic thin film recording disk of claim77 wherein the temperature of the substrate is heated to a temperaturewithin a range of 200° C. to 250° C.
 79. The magnetic thin filmrecording disk of claim 77 wherein the substrate is heated to atemperature within a range of 75° C. to 250° C. during the sputteringprocess.
 80. A magnetic thin film recording disk formed by a series ofsequential sputtering processes within an environment of a low pressureinert gas, comprising:a substrate characterized by a surface havingtexturing prior to any sputtering operation contributing to ananisotropic orientation of coercivity in the circumferential directionwhile not interfering with fly characteristics of a recording headacross the recording disk; a thin film nucleating layer, substantiallyfree of oxidation, deposited above the textured surface by a firstsputtering process; a thin film magnetic layer, substantially free ofoxidation, deposited above the nucleating layer by a second sputteringprocess and having an anisotropic orientation of coercivity in thecircumferential direction; and a thin film protective layer depositedabove the magnetic layer by a third sputtering process.
 81. The magneticthin film recording disk of claim 80, wherein the temperature of thesubstrate is within a range of 200° C. to 250° C. during the sputteringprocess.
 82. The magnetic thin film recording disk of claim 80, whereinthe nucleating layer contains chromium.
 83. The magnetic thin filmrecording disk of claim 80, wherein the magnetic layer contains ahexagonal closed packed cobalt alloy which has a C-axis orientationsubstantially parallel to the surface of the substrate.
 84. The magneticthin film recording disk of claim 80, wherein the magnetic layercontains a hexagonal closed packed cobalt alloy which has a C-axisorientation substantially in the circumferential direction.
 85. Themagnetic thin film recording disk of claim 80 wherein the substrate isheated to a temperature within a range of 75° C. to 250° C. during thesputtering process.
 86. The magnetic thin film recording disk of claim80 wherein the texturing, prior to any sputtering operation, encouragesa circular anisotropic orientation of crystal growth during sputtering.87. A magnetic thin film recording disk formed by a series of sequentialsputtering processes within an environment of a low pressure inert gas,comprising:a substrate having a nickel phosphorous surface layer, thesubstrate including aluminum, the substrate characterized by a surfacehaving texturing prior to any sputtering operation contributing to ananisotropic orientation of coercivity in the circumferential directionwhile not interfering with fly characteristics of a recording headacross the recording disk; a thin film nucleating layer containingchromium, substantially free of oxidation, deposited over the texturednickel phosphorous surface by a first sputtering process; a thin filmmagnetic layer containing a hexagonal close-packed cobalt alloydeposited over the nucleating layer by a second sputtering process andhaving an anisotropic orientation of coercivity in the circumferentialdirection; and a thin film protective layer containing carbon depositedover the magnetic layer by a third sputtering process.
 88. The magneticthin film recording disk of claim 87 wherein the temperature of thesubstrate is heated to a temperature within a range of 200° C. to 250°C.
 89. The magnetic thin film recording disk of claim 87 wherein thesubstrate is heated to a temperature within a range of 75° C. to 250° C.during the sputtering process.
 90. The magnetic thin film recording diskof claim 87 wherein the texturing, prior to any sputtering operation,encourages a circular anisotropic orientation of crystal growth duringsputtering.